Cutting Devices and Methods

ABSTRACT

Cutting devices useful for cutting objects or materials are described. Examples of cutting devices useful for creating avulsions in animals, such as human beings, are described. A cutting device includes an elongate main body having proximal and distal ends. A first portion of the main body has a cross-sectional shape that substantially lacks flat surfaces and a second portion of the main body has a cross-sectional shape having one, two or more flat surfaces. The distal end defines a hook having one or more sharpened edges disposed within the notch of the hook. Methods of making cutting devices are also described.

FIELD

The disclosure relates to cutting devices. Particular embodiments areuseful as medical devices for creating avulsions in animals, such ashuman beings. For example, embodiments are useful as medical devices inthe removal of synechiae in the venous system. Embodiments are alsouseful for clipping chordae tendineae from surrounding heart tissue.Embodiments can be used for cutting non-biological material, also. Forexample, embodiments are useful for cutting sutures, tubular plasticsheaths, and other materials.

BACKGROUND

It is desirable to cut objects and materials in a variety of processesand contexts. For example, cutting of biological material, such as atissue or other body structure, is sometimes desirable as part of atreatment process. For example, creation of an avulsion—an injury inwhich a body structure is detached from its normal point of attachmentto another body structure—is sometimes performed to remove leaflets ofan incompetent venous valve. Also, synechiae can be cut duringmanagement of post thrombotic syndrome and tendons and other connectivetissues can be cut to reposition or remove a particular tissue. Forexample, in certain procedures, it may be desirable to clip the chordaetendineae. Cutting of non-biological material, such as plastics, is alsodesirable in a variety of processes and contexts, including the makingand use of various medical devices.

There are several cutting devices and methods known in the art. A needremains, however, for improved devices and methods.

DESCRIPTION OF FIGURES

FIG. 1 is a side view of an example cutting device.

FIG. 1A is an enlarged cross-sectional view of the cutting deviceillustrated in FIG. 1, taken along line 1A-1A.

FIG. 1B is an enlarged cross-sectional view of the cutting deviceillustrated in FIG. 1, taken along line 1B-1B.

FIG. 1C is an enlarged cross-sectional view of the cutting deviceillustrated in FIG. 1, taken along line 1C-1C.

FIG. 2A is an enlarged top view of the distal end of the cutting deviceillustrated in FIG. 1.

FIG. 2B is an enlarged side view of the distal end of the cutting deviceillustrated in FIG. 1.

FIG. 3 is a side view of another example cutting device.

FIG. 3A is an enlarged cross-sectional view of the cutting deviceillustrated in FIG. 3, taken along line 3A-3A.

FIG. 4 is an enlarged top view of the distal end of an examplealternative cutting device.

FIG. 5 is a flowchart illustration of an example method of making acutting device.

FIG. 6 is a flowchart illustration of another example method of making acutting device.

FIG. 7 is an enlarged top view of the distal end of another examplecutting device.

DESCRIPTION OF EXAMPLE EMBODIMENTS

The following detailed description and the appended drawings describeand illustrate various example embodiments of cutting devices andmethods useful in creating avulsions in animals. The description andillustration of these examples are provided to enable one skilled in theart to make and use a cutting device useful in creating avulsions inanimals. They are not intended to limit the scope of the claims in anymanner.

As used herein, the term “avulsion,” and grammatically related terms,refers to an intentionally-introduced injury in which a body structureis detached from its normal point of attachment to another bodystructure. The term does not require a particular type of detachmentbetween the body structures. Indeed, the term includes any type ofdetachment between body structures. Non-limiting examples of types ofdetachment include tearing, cutting and clipping. Also, the term doesnot require that either of the body structures be any particular type ofbody structure. Indeed, each of the body structures can be any type ofbody structure. Non-limiting examples of types of body tissues includetissues, portions of tissue, connective tissues, nerve tissue, organs,and portions of organs. Non-limiting examples of specific avulsionsinclude detachment of a valve leaflet from a vessel wall by tearing thevalve leaflet away from the wall, cutting of synechiae, clipping oftendons, such as the chordae tendineae, and thromboectomy.

As used herein, the term “wire,” and grammatically related terms, refersto a single strand of material. The term does not require a particularmaterial. Indeed, the term includes any type of material. Non-limitingexamples of types of materials include metals, including alloys,polymeric materials, natural materials, flexible materials, and stiffmaterials. Non-limiting examples of specific materials include stainlesssteel; a shape memory material, such as a nickel titanium alloy; and aplastic material, such as nylon. Combinations of materials can also beused. For examples, a metal core can be partially or completely coveredby another material, such as a plastic. Also, the term does not requirea particular configuration of the material. Non-limiting examples ofpossible configurations include rods and ribbons of materials. Also, theterm does not require any particular cross-sectional shape for thematerial. Non-limiting examples of possible cross-sectional shapesinclude circular, elliptical, square and rectangular cross-sectionalshapes.

FIGS. 1, 1A, 1B, 1C, 2A, and 2B illustrate an example cutting device 10.The cutting device 10 includes an elongate main body 12 extendingbetween a proximal end 14 and a distal end 16. The main body 12 can becoiled on itself to form a loop 18. The distal end 16 defines a hook 20.

The main body 12 includes a first axial portion 22 having a circularcross-sectional shape and a second axial portion 24 having asubstantially rectangular cross-sectional shape. As best illustrated inFIGS. 1B and 1C, the second axial portion 24 has first 26 and second 28opposing surfaces. A third axial portion 23 is disposed axially betweenthe first 22 and second 24 axial portions. As best illustrated in FIG.2B, the third axial portion 23 defines a sloped surface 42 thattransitions from the circular cross-sectional shape of the first axialportion 22 to the rectangular cross-sectional shape of the second axialportion 24. Thus, the axial first portion 22 of the main body 12 has across-sectional shape with no flat surfaces and the second axial portion24 of the main body 12 has a cross-sectional shape having at least twoor more flat or substantially flat surfaces.

As best illustrated in FIG. 2A, hook 20 is defined by a bend 30 in mainbody 12 that forms opposing first 32 and second 34 arms, each of whichcomprise a portion of the main body 12. In the illustrated embodiment,the second arm 34 terminates in a rounded surface 35. Inclusion ofrounded surface 35 provides an atraumatic tip to the cutting device 10,which may be advantageous for cutting devices intended to be used asmedical devices.

The bend 30 has angle α and forms notch 36 comprising an open spacebetween first 32 and second 34 portions of the main body 12. A firstsharpened edge 38 is disposed on the side of the first portion 32 of themain body 12 that faces the notch 36. An optional second sharpened edge,not illustrated with the first example embodiment, can be disposed onthe side of the second portion 34 of the main body 12 that faces thenotch 36. Accordingly, if an optional second sharpened edge is included,the sharpened edges are disposed on opposing sides of notch 36.

Inclusion of a second sharpened edge is optional. A skilled artisan willbe able to determine if inclusion of a second sharpened edge is desiredfor a cutting device according to a particular embodiment based onvarious considerations, including the nature of the material with whichthe cutting device is intended to be used. The inventors have determinedthat inclusion of only a single sharpened edge, such as in the exampleembodiment illustrated in FIGS. 1, 1A, 1B, 1C, 2A, and 2B, is suitableand sufficient for a cutting device intended to be used for cuttingbiological tissue, such as chordae tendineae.

Each sharpened edge included in a cutting device according to anembodiment can have any suitable structure and relative position on therespective portion of the main body. The example cutting device 10includes a sharpened edge 38 having a suitable structure and position.As best illustrated in FIG. 2A, the sharpened edge 38 comprises a rampedsurface 39 that terminates in an interface 41 with the first surface 26of the second portion 24 of the main body 12. Opposite interface 41,ramped surface 39 terminates in leading edge 43. At its distal end,ramped surface 39 slopes downward from interface 41 to leading edge 43along wall portion 45, which is an extension of the inwardly-orientedside of the second arm 34 of the hook 20 and which lies on a plane thatis substantially perpendicular to a plane on which the first surface 26of the second portion 24 of the main body 12 lies. Thus, as bestillustrated in FIG. 2A, the sharpened edge 38 in the example embodimenthas a generally triangular shape.

The first axial portion 22 can have any suitable axial length thatcomprises a portion of the total axial length of the main body 12. Theaxial length of the first axial portion 22 is measured from the terminalsurface 15 of the proximal end 14 of the main body 12 to the transversemidpoint on the sloped surface 42 of the third axial portion 23 of themain body 12. In the illustrated embodiment, the first axial portion 22has an axial length that is about 95% of the total axial length of themain body 12. The inventors have determined that this axial lengthprovides desirable characteristics for the cutting device 10, includingease of handling and a minimal length over which additional formingtechniques need to be applied during fabrication. A skilled artisan canselect a suitable axial length for a first axial portion of a main bodyin a cutting device according to a particular embodiment based onvarious considerations, including a desired size of the hook as comparedto the total axial length of the main body. Examples of suitable axiallengths for a first axial portion in an embodiment include an axiallength that is between about 50% and about 99% of the total axial lengthof the main body, an axial length that is between about 60% and about99% of the total axial length of the main body, an axial length that isbetween about 70% and about 99% of the total axial length of the mainbody, an axial length that is between about 80% and about 99% of thetotal axial length of the main body, an axial length that is betweenabout 90% and about 99% of the total axial length of the main body, anaxial length that is between about 95% and about 99% of the total axiallength of the main body, an axial length that is between about 96% andabout 99% of the total axial length of the main body, an axial lengththat is between about 97% and about 99% of the total axial length of themain body, and an axial length that is between about 98% and about 99%of the total axial length of the main body.

Similarly, the second axial portion 24 can have any suitable axiallength 25 that comprises a portion of the total axial length of the mainbody 12. As best illustrated in FIG. 2A, the axial length 25 of thesecond axial portion 24 is measured from the transverse midpoint on thesloped surface 42 of the third axial portion 23 of the main body 12 tothe terminal surface 17 of the distal end 16 of the main body 12. In theillustrated embodiment, the second axial portion 24 has an axial lengththat is about 5% of the total axial length of the main body 12. Theinventors have determined that this axial length provides desirablecharacteristics for the cutting device 10, including ease of handlingand a minimal length along which additional forming techniques areapplied during fabrication. A skilled artisan can select a suitableaxial length for a second axial portion of a main body in a cuttingdevice according to a particular embodiment based on variousconsiderations, including a desired size of the hook as compared to thetotal axial length of the main body. Examples of suitable axial lengthsfor a second axial portion in an embodiment include an axial length thatis between about 1% and about 50% of the total axial length of the mainbody, an axial length that is between about 1% and about 40% of thetotal axial length of the main body, an axial length that is betweenabout 1% and about 30% of the total axial length of the main body, anaxial length that is between about 1% and about 20% of the total axiallength of the main body, an axial length that is between about 1% andabout 10% of the total axial length of the main body, an axial lengththat is between about 1% and about 5% of the total axial length of themain body, an axial length that is between about 1% and about 4% of thetotal axial length of the main body, an axial length that is betweenabout 1% and about 3% of the total axial length of the main body, and anaxial length that is between about 1% and about 2% of the total axiallength of the main body.

The hook 36 can have any suitable axial length 37 that comprises aportion of the axial length 25 of the second axial portion 24 of themain body 12. As best illustrated in FIG. 2A, the axial length 37 of thehook 36 is measured from the terminal surface 17 of the distal end 16 ofthe main body 12 to the transverse midpoint on the sloped surface 42 ofthe third axial portion 23 of the main body 12. In the illustratedembodiment, the hook 16 has an axial length 37 that is about 50% of theaxial length 25 of the second axial portion 24 of the main body 12. Theinventors have determined that this axial length provides desirablecharacteristics for the cutting device 10, including stability of thehook 16. A skilled artisan can select a suitable axial length for a hookin a cutting device according to a particular embodiment based onvarious considerations, including a desired size of the hook. Examplesof suitable axial lengths for a hook in an embodiment include an axiallength that is between about 5% and about 95% of the axial length of thesecond axial portion of the main body, an axial length that is betweenabout 10% and about 90% of the axial length of the second axial portionof the main body, an axial length that is between about 20% and about80% of the axial length of the second axial portion of the main body, anaxial length that is between about 30% and about 70% of the axial lengthof the second axial portion of the main body, an axial length that isbetween about 40% and about 60% of the axial length of the second axialportion of the main body, and an axial length that is between about 45%and about 55% of the axial length of the second axial portion of themain body.

The hook 20 can define any suitable has angle α. As best illustrated inFIG. 2A, the angle α of the hook 20 is measured between the lengthwiseaxis l₁ of the first arm 32 and the lengthwise axis l₂ of the second arm34. In the illustrated embodiment, the angle α is about 45°. Theinventors have determined that this angle provides desirablecharacteristics for the cutting device 10, including a desired balancebetween access to the sharpened edges 38, 40 inside the notch 36 andprotection from unwanted exposure to the sharpened edges 38, 40. Askilled artisan can select a suitable angle for a hook in a cuttingdevice according to a particular embodiment based on variousconsiderations, including the size of the body structure with which thecutting device is intended to be used. Examples of suitable angles for ahook in an embodiment include an angle that is between about 10° andabout 90°, an angle that is between about 20° and about 80°, an anglethat is between about 30° and about 70°, an angle that is between about40° and about 60°, an angle that is between about 40° and about 50°, anangle that is about 90°, an angle that is about 60°, an angle that isabout 45°, and an angle that is about 30°.

In the illustrated embodiment, the cutting device 10 includes only asingle sharpened edge 38. It is noted, though, that any suitable numberand arrangement of sharpened edges can be included in a cutting deviceaccording to a particular embodiment and a skilled artisan will be ableto select an appropriate number of sharpened edges for a cutting deviceaccording to a particular embodiment based on various considerations,including the nature, size and overall configuration of the bodystructure with which the cutting device is intended to be used and thenature of the material forming the cutting device. Examples of suitablenumbers and arrangements of sharpened edges include a single sharpenededge that extends on both the first and second arms of the hook, firstand second sharpened edges disposed on opposing sides of the hook andseparated by a non-sharpened surface, such as a non-sharpened surfacedisposed in a bend positioned between the first and second arms, aseries of sharpened edges with non-sharpened surfaces disposed betweenthe individual sharpened edges of the series of sharpened edges, andfirst and second series of sharpened edges with non-sharpened surfacesdisposed between the individual sharpened edges of each of the first andsecond series of sharpened edges.

The structure of cutting device 10 provides two levels of control overthat which can and cannot be cut by the cutting device 10. As a firstlevel of control, the length of the second arm 34 and angle αcooperatively limit the size of objects and materials that can fitwithin the open space of the notch 36. If an object or item does not fitwithin the open space of the notch 36, it cannot contact the cuttingedge 38 and, as a result, cannot be cut by the cutting device 10. As asecond level of control, the size of the sharpened edge 38, and thelength of the leading edge 43 in particular, define the maximum lengthalong which an object or material that fits within the open space of thenotch 36 can be cut. If the object or material has a dimension that isless than the length of the leading edge 43, the cutting device 10 willbe able to fully cut the object or material into separate pieces,assuming the cutting edge 38 can cut through the object or material.However, if the object or material fits within the open space of thenotch 36 but lacks a dimension that is less than the length of theleading edge 43, the cutting device 10 will not be able to fully cut theobject or material into separate pieces and will likely only be able tonick the object or material, which may be desirable. By varying thesecomponents of the structure of the cutting device, a skilled artisanwill be able to make a cutting device according to an embodiment thatprovides desirable cutting properties for a particular object ormaterial.

FIGS. 3 and 3A illustrate another cutting device 110. The cutting device110 is similar to the cutting device 10 illustrated in FIG. 1 anddescribed above, except as detailed below. Thus, the cutting device 110includes an elongate main body 112 extending between a proximal end 114and a distal end 116. The main body 112 can be coiled on itself to forma loop 118. The distal end 116 defines a hook 120. The main body 112includes a first axial portion 122 having a circular cross-sectionalshape and a second axial portion 124 having a substantially rectangularcross-sectional shape. The second axial portion 124 has first 126 andsecond 128 opposing and flat surfaces. A third axial portion 123 isdisposed axially between the first 122 and second 124 axial portions.Hook 120 is defined by a bend 130 in main body 112 that forms opposingfirst 132 and second 134 arms, each of which comprise a portion of themain body 112. The bend 130 forms notch 136 comprising an open spacebetween first 132 and second 134 portions of the main body 112. A firstsharpened edge 138 is disposed on the side of the first portion 132 ofthe main body 112 that faces the notch 136. Similarly, a secondsharpened edge 140 is disposed on the side of the second portion 134 ofthe main body 112 that faces the notch 136. In this embodiment, each ofthe first 138 and second 140 sharpened edges comprises a ramped surfaceextending from a leading edge to an interface with a portion of the mainbody 112.

In this embodiment, as best illustrated in FIG. 3, main body 112includes a pre-defined curve 150 that is disposed proximal of the distalend 116 of the main body 112. Inclusion of a pre-defined curve in acutting device according to an embodiment may be advantageous forcutting devices intended to be used on tissues or in locations thatrequire navigation of a tortuous path to achieve the desired avulsion.If included, the pre-defined curve can have any suitable size andconfiguration. In the illustrated embodiment, as best shown in FIG. 3,pre-defined curve 150 has radius of curvature r that is about 200% ofthe axial length 125 of the second axial portion 124 of the main body112. The inventors have determined that this radius of curvatureprovides desirable characteristics for a cutting device intended forclipping chordae tendineae. A skilled artisan can select a suitableradius of curvature for a pre-defined curve in a cutting deviceaccording to a particular embodiment based on various considerations,including the size, nature, location and access route of the bodystructure with which the cutting device is intended to be used. Examplesof suitable radii of curvature for a pre-defined curve in an embodimentinclude a radius of curvature that is between about 25% and about 500%of the axial length of the second axial portion of the main body, aradius of curvature that is between about 50% and about 400% of theaxial length of the second axial portion of the main body, a radius ofcurvature that is between about 75% and about 300% of the axial lengthof the second axial portion of the main body, a radius of curvature thatis between about 100% and about 200% of the axial length of the secondaxial portion of the main body, a radius of curvature that is about 100%of the axial length of the second axial portion of the main body, aradius of curvature that is about 125% of the axial length of the secondaxial portion of the main body, a radius of curvature that is about 150%of the axial length of the second axial portion of the main body, aradius of curvature that is about 175% of the axial length of the secondaxial portion of the main body, and a radius of curvature that is about200% of the axial length of the second axial portion of the main body.

If included, the pre-defined curve can have any suitable structuralarrangement relative to other portions of the cutting device. In theillustrated embodiment, as best shown in FIG. 3, the pre-defined curve150 is contained within a first plane that is different than a secondplane that contains the hook 120. In FIG. 3, the first plane is theplane of the drawing sheet and the second plane is a plane that isdisposed perpendicular to the first plane. The inventors have determinedthat this structural arrangement provides desirable characteristics fora cutting device intended for clipping chordae tendineae. Also, theinventors have determined that this structural arrangement provides acutting device that is suitable for cutting objects or materials thatextend generally parallel to the elongate main body. In theseembodiments, rotation of the main body on the lengthwise axis of themain body results in rotation of the hook of the cutting device in amanner that catches the object or material to be cut. Pulling on theelongate main body after catching the object or material results incutting of the object or material, even when the object or materialextends generally parallel to the elongate main body.

A skilled artisan can select a suitable structural arrangement for apre-defined curve in a cutting device according to a particularembodiment based on various considerations, including the size, nature,location and access route of the body structure with which the cuttingdevice is intended to be used. Examples of suitable structuralarrangement for a pre-defined curve in an embodiment include astructural arrangement in which the pre-defined curve is contained on afirst plane that is different from a second plan that contains the hookof the cutting device, a structural arrangement in which the pre-definedcurve is contained on a first plane that is perpendicular to a secondplane that contains the hook, a structural arrangement in which thepre-defined curve is contained on a first plane that is substantiallyperpendicular to a second plane that contains the hook, and a structuralarrangement in which the pre-defined curve is contained on a plane thatalso contains the hook.

FIG. 4 illustrates the distal end of an example alternative cuttingdevice 110′ in which the pre-defined curve 150′ is disposed on a planethat also contains the hook 120′. In FIG. 4, the plane that contains thepre-defined curve 150′ and the hook 120′ is the plane of the drawingsheet. In this alternative embodiment, the first arm 132′ defines aseries of sharpened edges 160′ with non-sharpened surfaces 162′ disposedbetween pairs of sharpened edges of the series of sharpened edges 160′.The second arm 134 defines a single sharpened edge 140′. Also, the mainbody 112′ defines an enlarged opening 164′ at the base of the notch136′. Inclusion of an enlarged opening 164′ may enhance engagement ofbody structures and/or provide a degree of tactile feedback during useof the cutting device 110′.

The cutting devices can be made from any suitable material. Skilledartisans will be able to select an appropriate material for a cuttingdevice according to a particular embodiment based on variousconsiderations, including the nature of the avulsion the cutting deviceis intended to create. Examples of suitable materials include metals,plastics and other polymeric materials, other materials used in themanufacture of conventional cutting devices, and newly-developedmaterials determined to be suitable for use in cutting devices.Stainless steel is considered advantageous at least because of itswell-characterized nature, wide acceptance as a material for use incutting devices that contact body structures, workable nature, and otherfactors. The inventors have determined that use of a stainless steel rodhaving a circular or substantially circular cross-sectional shape isparticularly advantageous. Use of stainless steel, however, isconsidered optional and a skilled artisan may determine that anothermaterial is desirable or advantageous for us in a cutting deviceaccording to a particular embodiment.

The cutting devices can be fabricated in any suitable manner and usingany suitable technique. Skilled artisans will be able to select anappropriate technique for fabricating a cutting device according to aparticular embodiment based on various considerations, including thenature of the material used for cutting device. Example techniques thatcan be used in the fabrication of a cutting device according to anembodiment include extruding, casting, and forging.

The inventors have developed methods of making cutting devices accordingto an embodiment. FIG. 5 is a flowchart illustration of an examplemethod 200 of making a cutting device. An initial step 210 comprisesbending a distal end of a wire having a main body, a proximal end and adistal end such that a distal tip defining an angle is formed. Anotherstep 212 comprises forming the distal end such that the angle of thedistal tip changes to form a hook having first and second opposing arms.Another step 214 comprises flattening a portion of the main body thatincludes the hook. Another step 216 comprises sharpening a surface onthe inside of the hook. An optional step can include sharpening anothersurface on the inside of the hook.

Step 210 can be accomplished using any suitable technique and to anysuitable degree. For example, for stainless steel wires, bending thedistal end of a wire by hand or with a simple hand tool, such as a pairof pliers, is suitable. Also, any suitable angle can be achieved as aresult of this step. If a roll-forming technique is used in step 214, asdescribed below, the inventors have determined that an angle that isbetween about 175° and about 180° is suitable. An angle that issubstantially 180° is also considered suitable, and can be achieved bybending the wire back on itself as much as possible.

Step 212 can be accomplished using any suitable technique and to anysuitable degree. For example, the distal end can be formed by hand orwith a suitable hand tool. In most methods, it will be desirable to formthe distal end such that the angle of the distal tip lessens. Forexample, the angle can be changed from the angle achieved in step 210 toa smaller angle of about 135°, which would provide a desirable hookangle of about 45°, as described above.

Step 214 can be accomplished using any suitable technique and to anysuitable degree. For example, the distal end can be hammered flat or canbe passed through rollers such that it is roll-formed to a flatconfiguration. Roll-forming is considered advantageous at least becauseit enables steps 212 and 214 to be conducted simultaneously. Forexample, when the distal end is passed through rollers to flatten it,the distal tip responds by opening a bit to form the hook. Whileconsidered advantageous, simultaneous performance of steps 212 and 214is optional.

In an example method, step 214 comprises repeatedly passing the distalend through rollers. For example, in one example method, the distal endis passed through rollers multiple times. In one example method, theseparating distance between the rollers is reduced before eachsubsequent pass of the distal end through the rollers. This provides agradual reduction in the thickness of the distal end of the device,which provides desirable characteristics for the resulting cuttingdevice.

Step 216 can be accomplished using any suitable technique. Examples ofsuitable techniques include grinding and etching. A skilled artisan willbe able to select a suitable sharpening technique for a method accordingto a particular embodiment based on various considerations, includingthe nature of the material of the wire. The inventors have determinedthat one or more passes of a whetstone across the surface of the wire isa suitable sharpening technique for methods in which the wire comprisesa metal.

Various additional optional steps can be included in a particularmethod. For example, if it is desired to include an atraumatic tip onthe distal end of the cutting device, an additional step of rounding anend of the wire can be included. If included, a rounding step can beaccomplished using any suitable technique, such as be grinding the endto form a rounded surface, and can be performed at any suitable point inthe method, including before or after step 210. Also, a step of buffinga portion of the distal end can be included. If included, the buffingstep is advantageously done until a mirror finish is achieved, and isadvantageously performed prior to the step 216 of sharpening a surface.A step of electropolishing the distal end can be included. If includedthe electropolishing step is advantageously performed after the step 216of sharpening a surface.

Also, an additional step of altering the length of one of the first andsecond opposing arms of the hook formed by performance of step 212 canbe included. If included, this step can be accomplished using anysuitable technique, such as cutting the arm to a shorter length.

FIG. 6 is a flowchart illustration of another example method 300 ofmaking a cutting device. An initial step 310 comprises bending a distalend of a wire having a main body, a proximal end and a distal end suchthat a distal tip defining an angle is formed. Another step 312comprises forming the distal end such that the angle of the distal tipchanges to form a hook. Another step 314 comprises flattening a portionof the main body that includes the hook. Another step 316 comprisessharpening a surface on the inside of the hook. Another step 318comprises forming a curve in the wire at a point proximal of the distalend of the wire.

Steps 310, 312, 314, 316 can be accomplished using any suitabletechnique, including those described above in connection with method 200illustrated in FIG. 5. Step 318 can be also be accomplished using anysuitable technique, including bending a portion of the wire with a handtool or shaping a portion of the wire with a roller.

EXAMPLE

FIG. 7 illustrates the distal end of an example cutting device 400 withvarious dimensional references. As described above, a cutting deviceaccording to and embodiment can have any suitable dimensions. Thefollowing provides examples of various dimensions and dimensional ratiosthe inventors have determined to be suitable for cutting devicesaccording to a particular embodiment that is well-suited for clippingchordae tendineae.

A suitable length for length a is between about 0.05″ and about 0.2″. Alength of between about 0.0625″ and about 0.125″ is also suitable forlength a. A length of about 0.1″ is also considered suitable for lengtha.

A suitable length for length b is between about 0.2″ and 2″. A length ofbetween about 0.2″ and about 0.5″ is also suitable for length b. Alength of about 0.25″ is also considered suitable for length b.

A suitable sum of widths c and d is between about 0.01″ and about 0.05″.A sum of between about 0.025″ and about 0.035″ is also suitable for thesum of widths c and d. A sum of about 0.030″ is also considered suitablefor the sum of widths c and d.

A suitable ratio of lengths a and b is between about 1:2 and about 1:4.

A suitable angle for angle e is between about 15° and about 50°. Anangle of between about 25° and about 35° is also considered suitable forangle e. An angle of about 30° is also considered suitable for angle e.

Those with ordinary skill in the art will appreciate that variousmodifications and alternatives for the described and illustratedembodiments can be developed in light of the overall teachings of thedisclosure. Accordingly, the particular structures and methods disclosedare intended to be illustrative only and not limiting as to the scope ofthe invention, which is to be given the full breadth of the claims andany and all equivalents thereof.

We claim:
 1. A cutting device, comprising: an elongate main body havinga proximal end, a distal end, and a lengthwise axis, the elongate mainbody defining a first axial portion including the proximal end andextending along a first axial length of the elongate main body, and asecond axial portion including the distal end and extending along asecond, different axial length of the elongate main body; the firstaxial portion having a first cross-sectional shape; the second axialportion having a second cross-sectional shape that is different than thefirst cross-sectional shape and that defines at least one flat orsubstantially flat surface; the distal end defining a hook comprisingfirst and second opposing arms and a sharpened edge disposed on one ofthe first and second arms.
 2. The cutting device of claim 1, wherein thefirst cross-sectional shape is circular or substantially circular. 3.The cutting device of claim 2, wherein the second cross-sectional shapeis rectangular or substantially rectangular.
 4. The cutting device ofclaim 1, wherein the hook has a third axial length; and wherein thethird axial length is less than the second axial length.
 5. The cuttingdevice of claim 1, further comprising a second sharpened edge disposedon one of the first and second arms.
 6. The cutting device of claim 1,further comprising a second sharpened edge; and wherein the firstsharpened edge is disposed on the first arm and the second sharpenededge is disposed on the second arm.
 7. The cutting device of claim 1,wherein the first and second arms define a hook angle; and wherein thehook angle is an angle between about 30° and about 70°.
 8. The cuttingdevice of claim 1, wherein the first and second arms define a hookangle; and wherein the hook angle is an angle between about 40° andabout 60°.
 9. The cutting device of claim 1, wherein the first andsecond arms define a hook angle; and wherein the hook angle is an anglebetween about 40° and about 50°.
 10. The cutting device of claim 1,wherein the elongate main body includes a pre-defined curve disposedproximal to the distal end.
 11. The cutting device of claim 10, whereinthe pre-defined curve has a radius of curvature that is between about25% and about 500% of the second axial length.
 12. The cutting device ofclaim 10, wherein the pre-defined curve has a radius of curvature thatis between about 50% and about 400% of the second axial length.
 13. Thecutting device of claim 10, wherein the pre-defined curve has a radiusof curvature that is between about 75% and about 300% of the secondaxial length.
 14. The cutting device of claim 10, wherein thepre-defined curve has a radius of curvature that is between about 100%and about 200% of the second axial length.
 15. The cutting device ofclaim 10, wherein the pre-defined curve has a radius of curvature thatis about 200% of the second axial length.
 16. The cutting device ofclaim 10, wherein the pre-defined curve is contained within a firstplane and the hook is contained within a second plane.
 17. The cuttingdevice of claim 16, wherein the first and second planes are differentplanes.
 18. The cutting device of claim 17, wherein the second plane isdisposed perpendicular or substantially perpendicular to the firstplane.
 19. A cutting device, comprising: an elongate main body having aproximal end, a distal end, and a lengthwise axis, the elongate mainbody defining a first axial portion including the proximal end andextending along a first axial length of the elongate main body, a secondaxial portion including the distal end and extending along a second,different axial length of the elongate main body, and a pre-definedcurve disposed proximal to the distal end; the first axial portionhaving a first, substantially circular cross-sectional shape; the secondaxial portion having a second cross-sectional shape that defines atleast one flat or substantially flat surface; the distal end defining ahook comprising first and second opposing arms and a sharpened edgedisposed on one of the first and second arms; wherein the pre-definedcurve is contained within a first plane and the hook is contained withina second, different plane.
 20. A method of making a cutting device, themethod comprising: bending a distal end of a wire having a main body, aproximal end and a distal end such that a distal tip defining an angleis formed; forming the distal end such that the angle of the distal tipchanges to form a hook; flattening a portion of the main body thatincludes the hook; and sharpening a surface on the inside of the hook.